Automotive congestion, whether of roads, streets, highways or parking spaces, is due to excessive demand for these facilities, and causes harm to the commercial and personal productivity of the businesses and people living in the area near and surrounding congested roads and areas. Automotive congestion also raises the levels of noxious automotive emissions that have known air-quality and related health effects and either concentrate in that local area or may spread more widely. Furthermore, automotive congestion is known to raise the risk of personal injury, death, or property damage due to crashes for those vehicles that are moving on congested facilities.
The ability of fuel taxes to financially support road building, operation and maintenance is waning as vehicles become more fuel efficient or use alternate fuels. Moreover, fuel taxation does not distinguish between congested and uncongested roads and times, hence offering road authorities no ability to design pricing signals that could be used to control congestion. (Pricing signals can be used to tell motorists it is more costly to drive in congested areas or at congested times.)
For these several reasons road and government authorities are studying and preparing for the impending change to a reduction in open (free) access to roads and an increase in more comprehensive road and parking pricing programs.
Since 2003, it has been expected that many jurisdictions such as, but not limited to countries, regions, states, provinces, and municipalities will begin engaging in large area road tolling and parking tolling, whether for purposes of controlling automotive congestion, automotive emissions and/or to raise revenue.
The technology of choice to enable this activity is Global Navigation Satellite Systems (GNSS). GNSS such as GPS, GLONASS, Galileo and the planned Compass have many applications. These range from guiding aircraft and weaponry to precision timing of financial transactions. In between are many tens of other applications such those for surveying, tracking, asset management and well-known land, water and personal navigation. Each of these applications has different accuracy, precision, speed and cost demands.
The task of using GNSS signals for charging for use of infrastructure such as roads or parking has a unique body of constraints and requirements that are not satisfied by GNSS-based navigation or asset tracking systems, in particular, a fully effective system must:                1. meter road use for tolling regardless of tolling architecture, including road segment(s), area, zone, cordon, distance-based, congestion pricing, time, location, and duration        2. meter parking use including surface lots, parking garages, and street parking        3. meter for liability insurance including time, distance, speed, acceleration, congestion, and location        4. work in built-up areas where radio signals may be severely disturbed by multipath        5. work while a vehicle is stationary        6. work while a vehicle is moving up to 150 mph,        7. work while a vehicle is changing speeds frequently (such as in heavy congestion)        8. be tamper-proof        9. incorporate a device that is remotely able to report its state of health regarding tamper or accidental failure        10. have no user interface for inputs (for security and greater reliability)        11. be able to communicate wirelessly over short distances to send data to a separate local device for applications, including 3rd-party applications, which may itself have a user interface        12. be able to communicate wirelessly over long distances        13. be able to operate anonymously to protect the ID and personal information about a vehicle owner or operator        14. be interoperable according to the requirements of the EU or other jurisdiction that requires interoperability with existing Electronic Toll Collection (ETC) Systems        15. be able to distinguish adjacent lanes of travel anywhere where multipath is not severe (e.g. outside of central business districts of cities)        16. incorporate an ability to pay negative tolls, for example to reward non-use of a vehicle at peak traffic times        17. be able to deconsolidate fees/charges due to multiple tolling authorities, multiple parking operators and at least one insurance firm from a single data feed from a vehicle        
For these requirements, a complete set of solutions is not currently available.
There are already numerous instances of GNSS-enabled devices in trial and even full systems in deployment for road-charging and insurance-metering systems. However, none of these work satisfactorily in harsh signal environments, in particular in the downtown “urban canyon” where they are most critically required. Specifically, existing devices have one or more of the following problems. They:                1. do not work satisfactorily in steep terrain or built-up areas (“urban canyon”)        2. do not provide an auditable evidentiary record such as is needed in non-refutable financial application (such as charging for road or parking use)        3. are difficult to maintain because they require volatile data on board (such as maps to be used in error masking algorithms for navigation, called “map-matching”).        4. are costly because they require assistance from other technology (such as inertial navigation or on-board map matching)        5. do not handle both privacy and auditability; moreover require an on-board payment capability to provide privacy        6. only handle one pricing regime, such as road-tolls or insurance premiums, and for only a single pricing authority in the case of GNSS-based tolling        
To build a workable and acceptable GNSS-based tolling system, all of these issues must be addressed.